The principal instruments used in this project are the Cameca MBX 2-50 KeV scanning electron beam microprobe and a Cameca MS-46 electron microprobe, each equipped with two wavelength dispersive spectrometers. Quantitative elemental analysis in volumes of the order of 10 to the -10 liter are possible using these instruments. The signal for some elements changes with time as a function of beam current-density, sample mass thickness and some other characteristics of the samples. A systematic quantitative study of the variables that affect stability of the signal has been undertaken to establish the ranges of values of these variables that permit usable results to be obtained.